Long-term comparison between perindopril and nifedipine in normotensive patients with type 1 diabetes and microalbuminuria

Angiotensin-converting-enzyme inhibitors and angiotensin receptor blockers for preventing the progression of diabetic kidney disease

BACKGROUND

Guidelines suggest that adults with diabetes and kidney disease receive treatment with angiotensin-converting-enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB). This is an update of a Cochrane review published in 2006.

OBJECTIVES

We compared the efficacy and safety of ACEi and ARB therapy (either as monotherapy or in combination) on cardiovascular and kidney outcomes in adults with diabetes and kidney disease.

SEARCH METHODS

We searched the Cochrane Kidney and Transplants Register of Studies to 17 March 2024 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included studies evaluating ACEi or ARB alone or in combination, compared to each other, placebo or no treatment in people with diabetes and kidney disease.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the risk of bias and extracted data. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes and mean difference (MD) or standardised mean difference (SMD) and 95% CI for continuous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

One hundred and nine studies (28,341 randomised participants) were eligible for inclusion. Overall, the risk of bias was high. Compared to placebo or no treatment, ACEi may make little or no difference to all-cause death (24 studies, 7413 participants: RR 0.91, 95% CI 0.73 to 1.15; I2 = 23%; low certainty) and with similar withdrawals from treatment (7 studies, 5306 participants: RR 1.03, 95% CI 0.90 to 1.19; I2 = 0%; low certainty). ACEi may prevent kidney failure (8 studies, 6643 participants: RR 0.61, 95% CI 0.39 to 0.94; I2 = 0%; low certainty). Compared to placebo or no treatment, ARB may make little or no difference to all-cause death (11 studies, 4260 participants: RR 0.99, 95% CI 0.85 to 1.16; I2 = 0%; low certainty). ARB have uncertain effects on withdrawal from treatment (3 studies, 721 participants: RR 0.85, 95% CI 0.58 to 1.26; I2 = 2%; low certainty) and cardiovascular death (6 studies, 878 participants: RR 3.36, 95% CI 0.93 to 12.07; low certainty). ARB may prevent kidney failure (3 studies, 3227 participants: RR 0.82, 95% CI 0.72 to 0.94; I2 = 0%; low certainty), doubling of serum creatinine (SCr) (4 studies, 3280 participants: RR 0.84, 95% CI 0.72 to 0.97; I2 = 32%; low certainty), and the progression from microalbuminuria to macroalbuminuria (5 studies, 815 participants: RR 0.44, 95% CI 0.23 to 0.85; I2 = 74%; low certainty). Compared to ACEi, ARB had uncertain effects on all-cause death (15 studies, 1739 participants: RR 1.13, 95% CI 0.68 to 1.88; I2 = 0%; low certainty), withdrawal from treatment (6 studies, 612 participants: RR 0.91, 95% CI 0.65 to 1.28; I2 = 0%; low certainty), cardiovascular death (13 studies, 1606 participants: RR 1.15, 95% CI 0.45 to 2.98; I2 = 0%; low certainty), kidney failure (3 studies, 837 participants: RR 0.56, 95% CI 0.29 to 1.07; I2 = 0%; low certainty), and doubling of SCr (2 studies, 767 participants: RR 0.88, 95% CI 0.52 to 1.48; I2 = 0%; low certainty). Compared to ACEi plus ARB, ACEi alone has uncertain effects on all-cause death (6 studies, 1166 participants: RR 1.08, 95% CI 0.49 to 2.40; I2 = 20%; low certainty), withdrawal from treatment (2 studies, 172 participants: RR 0.78, 95% CI 0.33 to 1.86; I2 = 0%; low certainty), cardiovascular death (4 studies, 994 participants: RR 3.02, 95% CI 0.61 to 14.85; low certainty), kidney failure (3 studies, 880 participants: RR 1.36, 95% CI 0.79 to 2.32; I2 = 0%; low certainty), and doubling of SCr (2 studies, 813 participants: RR 1.14, 95% CI 0.70 to 1.85; I2 = 0%; low certainty). Compared to ACEi plus ARB, ARB alone has uncertain effects on all-cause death (7 studies, 2607 participants: RR 1.02, 95% CI 0.76 to 1.37; I2 = 0%; low certainty), withdrawn from treatment (3 studies, 1615 participants: RR 0.81, 95% CI 0.53 to 1.24; I2 = 0%; low certainty), cardiovascular death (4 studies, 992 participants: RR 3.03, 95% CI 0.62 to 14.93; low certainty), kidney failure (4 studies, 2321 participants: RR 1.15, 95% CI 0.67 to 1.95; I2 = 29%; low certainty), and doubling of SCr (3 studies, 2252 participants: RR 1.18, 95% CI 0.85 to 1.64; I2 = 0%; low certainty). Comparative effects of different ACEi or ARB and low-dose versus high-dose ARB were rarely evaluated. No study compared different doses of ACEi. Adverse events of ACEi and ARB were rarely reported.

AUTHORS' CONCLUSIONS

ACEi or ARB may make little or no difference to all-cause and cardiovascular death compared to placebo or no treatment in people with diabetes and kidney disease but may prevent kidney failure. ARB may prevent the doubling of SCr and the progression from microalbuminuria to macroalbuminuria compared with a placebo or no treatment. Despite the international guidelines suggesting not combining ACEi and ARB treatment, the effects of ACEi or ARB monotherapy compared to dual therapy have not been adequately assessed. The limited data availability and the low quality of the included studies prevented the assessment of the benefits and harms of ACEi or ARB in people with diabetes and kidney disease. Low and very low certainty evidence indicates that it is possible that further studies might provide different results.

Comparative risk of new-onset hyperkalemia for antihypertensive drugs in patients with diabetic nephropathy: A Bayesian network meta-analysis

Several randomised controlled trials (RCTs) have evaluated the risk of hyperkalemia of antihypertensive drugs on diabetic nephropathy, yet the results are conflicting. We searched MEDLINE, Embase, The Cochrane Library, and Web of Science for RCTs investigating the risk of antihypertensive drugs on hyperkalemia in diabetic nephropathy from inception to May 31, 2020. Direct comparative meta-analysis showed that the proportion of patients with hyperkalemia was significantly higher in the ARB, aldosterone antagonist, renin inhibitor group than in the placebo group. Moreover, the risk of hyperkalemia in the ARB group was higher than that in the CCB group. Network meta-analysis showed the risk of hyperkalemia in the ARB, aldosterone antagonist, and renin inhibitor group was higher than in the placebo group, but there was no statistical difference between the CCB, ACEI, β blocker, endothelin inhibitor, and diuretic groups than in the placebo group. The possibility of antihypertensive drugs in risk of hyperkalemia being the worst treatment was aldosterone antagonist (98.8%), followed by ARB (73.8%), renin inhibitor (63.8%), diuretic (53.1%), ACEI (46.9%), β blocker (36.8%), endothelin inhibitor (35.2%), placebo (27.1%), and finally CCB (14.3.1%). Therefore, aldosterone antagonist seems worse than other antihypertensive drugs in the risk of hyperkalemia in patients with diabetic nephropathy.

Short- and long-term treatment with angiotensin-converting enzyme inhibitors or calcium channel blockers for the prevention of diabetic nephropathy progression: A meta-analysis

Treatments with angiotensin-converting enzyme (ACE) inhibitors or calcium channel blockers (CCBs) may delay the development of albuminuria in patients with early diabetic nephropathy. However, evidence in the literature has not been consistent. The present meta-analysis aimed to compare the short- and long-term therapeutic effects of ACE inhibitors and CCBs (when used separately) for preventing the progression of nephropathy in patients with diabetes mellitus. A comprehensive search of various databases was performed from inception until March 2015 for studies in the Chinese and English languages. Randomized controlled trials (RCTs) comparing the efficacy of ACE inhibitors with that of CCBs in patients with early diabetic nephropathy were considered. A total of 12 RCTs were included with a total of 947 patients. ACE inhibitors were indicated to be more effective in reducing the albumin excretion rate than CCBs after short-term treatments (<6 months) [mean difference (MD), 32.35; 95% confidence interval (CI), 31.62-33.07; P<0.00001]. There was no difference in serum creatinine values after treatment with either drug (MD, 8.7; 95% CI, -21.5-38.91; P=0.57). Data from six studies were used to compare long-term treatment effects (≥1 year). In terms of progression to normoalbuminuria, a marginal difference was obtained between the two drugs with better outcomes with ACE inhibitors [odds ratio (OR), 0.70; 95% CI, 0.49-1.00; P=0.05]. There was no statistically significant difference between ACE inhibitors and CCBs regarding the progression from microalbuminuria to macroalbuminuria (OR, 1.78; 95% CI, 0.82-3.87; P=0.15). In conclusion, the present study indicated that the antiproteinuric efficacy of CCBs may be less than that of ACE inhibitors after short-term treatment in patients with DN. However, both types of drugs are equally effective in reducing the progression of microalbuminuria to macroalbuminuria in the long term.

Treatment strategies for hypertension in patients with type 1 diabetes

INTRODUCTION

Type 1 diabetes mellitus (T1DM) is a chronic, autoimmune disease that is characterized by total absence of insulin production. Hypertension is a common comorbidity in T1DM with complex pathophysiology, while it is also a well-recognized risk factor for the development of cardiovascular disease (CVD), as well as other microvascular diabetic complications.

AREAS COVERED

The purpose of this review is to present the current definitions, epidemiological data and prevalence rates of hypertension in T1DM, as well as to describe current therapeutic options.

EXPERT OPINION

Hypertension affects around a third of the type 1 diabetic population, with higher prevalence rates in older individuals with longer disease duration. Although hypertension affects a substantial proportion of T1DM individuals, blood pressure control rates are disappointingly low. Alongside lifestyle modification, antihypertensive treatment should be initiated in those with blood pressure above 140/90 mmHg, with a systolic blood pressure target of 130 mmHg and lower, if tolerated. In those with established CVD or diabetic nephropathy, systolic blood pressure targets below 130 mmHg should be pursued. Initial pharmacotherapy should consist of a renin-angiotensin-aldosterone system inhibitor. There is an urgent need for good quality data regarding proper antihypertensive treatment initiation, optimal BP targets and optimal antihypertensive treatment for better clinical outcomes.

Comparative Efficacy and Safety of Antihypertensive Agents for Adult Diabetic Patients with Microalbuminuric Kidney Disease: A Network Meta-Analysis

BACKGROUND

Antihypertensive treatment mitigates the progression of chronic kidney disease. Here, we comparatively assessed the effects of antihypertensive agents in normotensive and hypertensive diabetic patients with microalbuminuric kidney disease.

METHODS

MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were systematically searched for randomized controlled trials (RCTs) comparing oral antihypertensive agents in adult diabetic patients with microalbuminuria. The primary efficacy outcome was reduction in albuminuria, and the primary safety outcomes were dry cough, presyncope, and edema. Random-effects pairwise and Bayesian network meta-analyses were performed to produce outcome estimates for all RCTs, only hypertensive RCTs, or only normotensive RCTs. Surface under the cumulative ranking (SUCRA) probability rankings were calculated for all outcomes. Sensitivity analyses on type 2 diabetes status, age, or follow-up duration were also performed.

RESULTS

A total of 38 RCTs were included in the meta-analyses. The angiotensin-converting enzyme inhibitor-calcium channel blocker (ACEI-CCB) combination therapy of captopril+diltiazem was most efficacious in reducing albuminuria irrespective of blood pressure status. However, the ACEI-angiotensin receptor blocker (ACEI-ARB) combination therapy of trandolapril+candesartan was the most efficacious in reducing albuminuria for normotensive patients, while the ACEI-CCB combination therapy of fosinopril+amlodipine was the most efficacious in reducing albuminuria for hypertensive patients. The foregoing combination therapies displayed inferior safety profiles relative to ACEI monotherapy with respect to dry cough, presyncope, and edema. With respect to type 2 diabetic patients with microalbuminuria, the Chinese herbal medicine Tangshen formula followed by the ACEI ramipril were the most efficacious in reducing albuminuria.

CONCLUSIONS

Trandolapril+candesartan appears to be the most efficacious intervention for reducing albuminuria for normotensive patients, while fosinopril+amlodipine appears to be the most efficacious intervention for reducing albuminuria for hypertensive patients. For practitioners opting for monotherapy, our SUCRA analysis supports the use of trandolapril and fosinopril in normotensive and hypertensive adult diabetic patients with microalbuminuria, respectively.

Angiotensin-converting enzyme inhibition in cardiovascular disease: evidence with perindopril

Perindopril is a long-acting, once-daily lipophilic angiotensin-converting enzyme inhibitor with high tissue angiotensin-converting enzyme affinity, lowering angiotensin II and potentiating bradykinin. Its efficacy, safety and tolerability are well established in the treatment of hypertension and heart failure. Moreover, large morbidity-mortality trials, such as the EUropean trial on Reduction Of cardiac events with Perindopril in stable coronary Artery disease (EUROPA) and Perindopril pROtection aGainst REcurrent Stroke Study (PROGRESS), have shown that antihypertensive treatment with perindopril reduces and prevents cardiovascular disease in a large range of patients with vascular diseases, whether hypertensive or not. Thus, the outcome of these and other trials support the concept of cardiovascular protective properties of angiotensin-converting enzyme inhibition with perindopril in addition to the obvious blood-pressure-lowering effect. Considering its properties and the gathered clinical evidence on efficacy and tolerability, perindopril fulfils the criteria of the latest guidelines for hypertension and cardiovascular disease management and should therefore be considered as a first-line antihypertensive agent, forming a consistent part of the comprehensive strategy against hypertension and related cardiovascular complications.

Changing trends in end-stage renal disease due to diabetes in the United kingdom

BACKGROUND

In some countries, diabetic kidney disease (DKD) is responsible for half of all new patients requiring renal replacement therapy (RRT). Understanding the relationship between early and later stages of DKD is important as it is a preventable cause of renal failure. This review aims to establish the trends in end-stage renal disease (ESRD) due to diabetes in the United Kingdom as the first step in this understanding.

METHODS

Using annual reports from the UK Renal Registry, we summarise the presentation, incidence, prevalence and survival of ESRD patients with diabetes over the last 10-15 years.

RESULTS

Between 1995 and 2009, initiation of RRT in diabetes patients increased from 12.3 to 27.6 patients per million population (pmp). These rates are approximately five times less than those of Caucasians in the United States suggesting fundamental differences in early DKD management. Survival of diabetic patients on dialysis has improved such that prevalent numbers on RRT increased from 47 to 117 pmp in a 12-year period. A longer time to prepare patients for RRT is strongly related with better outcomes. In 2002, 23% of all patients with diabetic nephropathy were referred late, within 90 days of RRT start; by 2009, this figure had fallen to 11.2%. Access to renal transplantation, the best form of RRT, has improved with almost 12.5% of new transplants occurring in patients with diabetes compared to 8.3% in 1997.

CONCLUSIONS

End Stage DKD is more extensively and better treated now than in the late 1990 s and coincides with a time of rapid expansion of UK renal services. More diabetes patients start RRT, patients are referred earlier and survive longer. The prevalence of end-stage DKD is 2.5 times what it was just over 10 years ago. However, across the United Kingdom, there still exists variation in the incidence and outcomes of end-stage DKD. That these figures have grown so much but are still dwarfed by other countries' burden of DKD merits further research. Further prevention of DKD is achievable for the United Kingdom and particularly critical for developing nations who can least afford the expensive 'option' of RRT.

Manidipine: A different dihydropyridine

Blood pressure (BP) plays an important role in the development and progression of cardiovascular disease. Moreover, hypertensive patients often have additional cardiovascular risk factors. Despite the abundance of antihypertensive drug categories, satisfactory BP regulation is often difficult to achieve. A major cause of this difficulty to properly manage BP is the less than optimal adherence of subjects to treatment. This is often due to the various adverse effects of the antihypertensive drugs. Calcium channel blockers (CCB) have an established efficacy for reducing BP. However, their side effect of peripheral edema is often a cause for the discontinuation of treatment. Manidipine holds some unique properties differentiating it from the rest of the CCB class. It has a better safety profile with a lower incidence of peripheral edema. Moreover, there are indications that manidipine holds additional beneficial attributes, such as improvement of renal function and decrease of insulin resistance.

Secondary prevention of CAD with ACE inhibitors: a struggle between life and death of the endothelium

Angiotensin-converting enzyme (ACE) inhibitors improve outcomes in patients with coronary artery disease (CAD), heart failure, and hypertension. This short review examines clinical evidence for such effects and the underlying mechanism of action. One potential mode of action for ACE inhibitors in CAD is blood pressure reduction. However, recent data suggest that the effects of ACE inhibitors on the endothelium may also be relevant in attenuating the progression of atherosclerosis. In CAD, chronic overexpression of tissue ACE disrupts the angiotensin II/bradykinin balance with a net result of endothelial dysfunction, mainly due to an increased rate of apoptosis. An imbalance between endothelial apoptosis (death) and its renewal from the bone marrow (life) causes discontinuity of the endothelial layer, favoring the initiation and progression of a biochemical sequence that leads to atherosclerosis, plaque rupture, and eventually acute coronary syndromes. There is clinical and experimental evidence that ACE inhibition improves the life and death cycle of the endothelium. By restoring the bradykinin/angiotensin II balance, ACE inhibition reduces the rate of endothelial apoptosis and experimental results suggest that ACE inhibition can also improve the production and mobilization of endothelial progenitor cells from bone marrow. We report our experience in this context with perindopril.

Angiotensin-converting enzyme inhibitors, angiotensin receptor blockers and combined therapy in patients with micro- and macroalbuminuria and other cardiovascular risk factors: a systematic review of randomized controlled trials

BACKGROUND

A recent clinical trial showed harmful renal effects with the combined use of angiotensin-converting enzyme inhibitors (ACEI) and angiotensin-II receptor blockers (ARB) in people with diabetes or vascular disease. We examined the benefits and risks of these agents in people with albuminuria and one or more cardiovascular risk factors.

METHODS

MEDLINE, EMBASE and Renal Health Library were searched for trials comparing ACEI, ARB or their combination with placebo or with one another in people with albuminuria and one or more cardiovascular risk factor.

RESULTS

Eighty-five trials (21,708 patients) were included. There was no significant reduction in the risk of all-cause mortality or fatal cardiac-cerebrovascular outcomes with ACEI versus placebo, ARB versus placebo, ACEI versus ARB or with combined therapy with ACEI + ARB versus monotherapy. There was a significant reduction in the risk of nonfatal cardiovascular events with ACEI versus placebo but not with ARB versus placebo, ACEI versus ARB or with combined therapy with ACEI + ARB versus monotherapy. Development of end-stage kidney disease and progression of microalbuminuria to macroalbuminuria were reduced significantly with ACEI versus placebo and ARB versus placebo but not with combined therapy with ACEI + ARB versus monotherapy.

CONCLUSIONS

ACEI and ARB exert independent renal and nonfatal cardiovascular benefits while their effects on mortality and fatal cardiovascular disease are uncertain. There is a lack of evidence to support the use of combination therapy. A comparative clinical trial with ACE, ARB and its combination in people with albuminuria and a cardiovascular risk factor is warranted.

Modulation of the cellular expression of circulating advanced glycation end-product receptors in type 2 diabetic nephropathy

Background. Advanced glycation end-products (AGEs) and their receptors are prominent contributors to diabetic kidney disease. Methods. Flow cytometry was used to measure the predictive capacity for kidney impairment of the AGE receptors RAGE, AGE-R1, and AGE-R3 on peripheral blood mononuclear cells (PBMCs) in experimental models of type 2 diabetes (T2DM) fed varied AGE containing diets and in obese type 2 diabetic and control human subjects. Results. Diets high in AGE content fed to diabetic mice decreased cell surface RAGE on PBMCs and in type 2 diabetic patients with renal impairment (RI). All diabetic mice had elevated Albumin excretion rates (AERs), and high AGE fed dbdb mice had declining Glomerular filtration rate (GFR). Cell surface AGE-R1 expression was also decreased by high AGE diets and with diabetes in dbdb mice and in humans with RI. PBMC expression of AGE R3 was decreased in diabetic dbdb mice or with a low AGE diet. Conclusions. The most predictive PBMC profile for renal disease associated with T2DM was an increase in the cell surface expression of AGE-R1, in the context of a decrease in membranous RAGE expression in humans, which warrants further investigation as a biomarker for progressive DN in larger patient cohorts.

Stretch reduces nephrin expression via an angiotensin II-AT(1)-dependent mechanism in human podocytes: effect of rosiglitazone

Increased glomerular permeability to proteins is a characteristic feature of diabetic nephropathy (DN). The slit diaphragm is the major restriction site to protein filtration, and the loss of nephrin, a key component of the slit diaphragm, has been demonstrated in both human and experimental DN. Both systemic and glomerular hypertension are believed to be important in the pathogenesis of DN. Human immortalized podocytes were subjected to repeated stretch-relaxation cycles by mechanical deformation with the use of a stress unit (10% elongation, 60 cycles/min) in the presence or absence of candesartan (1 microM), PD-123319 (1 microM), and rosiglitazone (0.1 microM). Nephrin mRNA and protein expression were assessed using quantitative real-time PCR, immunoblotting, and immunofluorescence, and the protein expression of AT(1) receptor and angiotensin II secretion were evaluated. Exposure to stretch induced a significant approximately 50% decrease in both nephrin mRNA and protein expression. This effect was mediated by an angiotensin II-AT(1) mechanism. Indeed, podocyte stretching induced both angiotensin II secretion and AT(1) receptor overexpression, podocyte exposure to angiotensin II reduced nephrin protein expression, and both the AT-1 receptor antagonist candesartan and a specific anti-angiotensin II antibody completely abolished stretch-induced nephrin downregulation. Similar to candesartan, the peroxisome proliferator-activated receptor (PPAR)-gamma agonist, rosiglitazone, also inhibited stretch-induced nephrin downregulation, suggesting interference with stretch-induced activation of the angiotensin II-AT(1) receptor system. Accordingly, rosiglitazone did not alter stretch-induced angiotensin II secretion, but it prevented AT(1) upregulation in response to stretch. These results suggest a role for hemodynamic stress in loss of nephrin expression and allude to a role of PPAR-gamma agonists in the prevention of this loss.

[Angiotensin converting enzyme inhibitors and calcium antagonists: a synergistic action for a better prevention of cardiovascular events]

Treatment of hypertension increasingly requires association of drugs. Among them, the association of calcium antagonists with angiotensin converting enzyme inhibitors is a new tempting approach since the two pharmaceutical classes have synergistic effects on blood pressure lowering and target organ protection whereas their effect is antagonistic for adverse events. Numerous large randomized clinical trials have validated this treatment strategy, and new fixed association are being developed. They apply to hypertensive patients, but also to coronary artery disease patients and more generally speaking to high cardiovascular risk subjects.

Diabetic nephropathy

Diabetic nephropathy is the leading cause of chronic renal disease and a major cause of cardiovascular mortality. Diabetic nephropathy has been categorized into stages: microalbuminuria and macroalbuminuria. The cut-off values of micro- and macroalbuminuria are arbitrary and their values have been questioned. Subjects in the upper-normal range of albuminuria seem to be at high risk of progression to micro- or macroalbuminuria and they also had a higher blood pressure than normoalbuminuric subjects in the lower normoalbuminuria range. Diabetic nephropathy screening is made by measuring albumin in spot urine. If abnormal, it should be confirmed in two out three samples collected in a three to six-months interval. Additionally, it is recommended that glomerular filtration rate be routinely estimated for appropriate screening of nephropathy, because some patients present a decreased glomerular filtration rate when urine albumin values are in the normal range. The two main risk factors for diabetic nephropathy are hyperglycemia and arterial hypertension, but the genetic susceptibility in both type 1 and type 2 diabetes is of great importance. Other risk factors are smoking, dyslipidemia, proteinuria, glomerular hyperfiltration and dietary factors. Nephropathy is pathologically characterized in individuals with type 1 diabetes by thickening of glomerular and tubular basal membranes, with progressive mesangial expansion (diffuse or nodular) leading to progressive reduction of glomerular filtration surface. Concurrent interstitial morphological alterations and hyalinization of afferent and efferent glomerular arterioles also occur. Podocytes abnormalities also appear to be involved in the glomerulosclerosis process. In patients with type 2 diabetes, renal lesions are heterogeneous and more complex than in individuals with type 1 diabetes. Treatment of diabetic nephropathy is based on a multiple risk factor approach, and the goal is retarding the development or progression of the disease and to decrease the subject's increased risk of cardiovascular disease. Achieving the best metabolic control, treating hypertension (<130/80 mmHg) and dyslipidemia (LDL cholesterol <100 mg/dl), using drugs that block the renin-angiotensin-aldosterone system, are effective strategies for preventing the development of microalbuminuria, delaying the progression to more advanced stages of nephropathy and reducing cardiovascular mortality in patients with diabetes.

Influence of T-calcium channel blocker treatment on deterioration of renal function in chronic kidney disease

Some calcium channel blockers (CCBs) have renoprotective effects. Our aim was to compare the effects of different subclasses of CCBs on the deterioration of renal function in chronic kidney disease (CKD). This is a prospective, observational cohort study in a single center. The subjects were 107 nondiabetic CKD patients. The rate of deterioration of estimated glomerular filtration rate (DeltaeGFR) was calculated by [last visit eGFR - baseline eGFR/follow-up duration]. Multivariate analysis was performed using the change in urinary protein (DeltaUP) and DeltaeGFR during follow-up as response variables. CCB subclasses were L-type in 76 patients, T- and L-type in 28 patients, and nondihydropyridines in 6 patients. Multiregression analysis indicated that higher baseline proteinuria (UP) and the use of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers were associated with the decrease of UP, while the use of L-type CCBs, prednisolone, and probucol was associated with the increase of UP. The use of T- and L-type CCBs, ACEIs and diuretics was associated with a good outcome in terms of DeltaeGFR, whereas chronic glomerulonephritis, polycystic kidney disease, and higher baseline eGFR and UP were associated with a poor outcome. It is suggested that the use of T- and L-type CCB among other subclasses may improve the outcome of patients with nondiabetic CKD in terms of renal function.

Optimizing the treatment of hypertension and stable coronary artery disease: clinical evidence for fixed-combination perindopril/amlodipine

BACKGROUND

Optimized management of hypertension and coronary artery disease (CAD) improves cardiovascular risk and outcomes, and prevents complications. This article reviews evidence for the fixed combination of the angiotensin-converting enzyme (ACE) inhibitor perindopril and the calcium channel blocker amlodipine.

METHODS

A literature search was performed in PubMed/MEDLINE to identify articles published in English between 1988 and March 2008 describing clinical trials, particularly outcome trials, or mechanisms of therapeutic action relevant to the use of combination therapy in patients with hypertension or stable coronary artery disease with an ACE inhibitor (perindopril) and a calcium channel blocker (amlodipine).

FINDINGS

Clinical trials indicate that this combination may have a positive impact on cardiovascular mortality and morbidity in hypertensive individuals. The two complementary mechanisms of action appear to work in synergy, leading to more efficient blood pressure lowering, improved fibrinolytic function, and reduction of secondary effects. This also represents a simplified management strategy for stable CAD. Perindopril has proven efficacy in the prevention of cardiovascular events and mortality in CAD patients, while amlodipine is widely used in the symptomatic management of CAD. Both aspects of guideline-recommended management of CAD are therefore addressed in a single tablet.

CONCLUSIONS

The clinical evidence for fixed-combination perindopril/amlodipine indicates it as a credible option for the optimization of the management of hypertension and CAD.

Chronic kidney disease at high altitude

With a prevalence of 10 to 11% in the general population, it is likely that many patients with chronic kidney disease will visit or reside in mountainous areas. Little is known, however, about whether short- or long-duration, high-altitude exposure poses a risk in this patient population. Given that many areas of the kidney are marginally oxygenated even at sea level and that kidney disease may result in further renal hypoxia and hypoxia-associated renal injury, there is concern that high altitude may accelerate the progression of chronic kidney disease. In this review, we address how chronic kidney disease and its management is affected at high altitude. We postulate that arterial hypoxemia at high altitude poses a risk of faster disease progression in those with preexisting kidney disease. In addition, we consider the risks of developing acute altitude illness in patients with chronic kidney disease and the appropriate use of medications for the prevention and treatment of these problems.

Lowering of proteinuria in response to antihypertensive therapy predicts improved renal function in late but not in early diabetic nephropathy: a pooled analysis

In late diabetic nephropathy (DN) the initial lowering of albumin excretion rate (AER) with antihypertensive therapy is proportional to the degree of subsequent preservation of glomerular filtration rate (GFR). Whether a similar relationship exists between AER and GFR in early diabetes is not known. The present analysis has compared AER and GFR responses to antihypertensive therapy in 33 published studies (77 treatment groups) of early and late DN in type 1 (T1) and type 2 (T2) diabetes, analyzed on an intention-to-treat basis. Prospective trials were included if the initial change in AER during the first year of therapy and the change in GFR during at least 2 years of follow-up could be estimated from group mean data. The initial % decreases in AER were 5.9 +/- 4.3 (T1), 10.5 +/- 5.4 (T2, normotensive) and 18.4 +/- 6.2 (T2, hypertensive) in early DN and 7.6 +/- 11.1 (T1) and 20.8 +/- 5.5 (T2) in late DN. The corresponding annual % rates of decline of GFR were 2.0 +/- 0.5 (T1), 1.6 +/- 0.5 (T2, normotensive) and 2.1 +/- 0.3 (T2, hypertensive) in early DN and 9.8 +/- 1.5 (T1) and 9.2 +/- 1.1 (T2) in late DN. AER and GFR responses in each treatment group were closely correlated in late nephropathy (T1, r = -0.67, p = 0.03; T2, r = 0.57, p = 0.02) but not in early nephropathy. In contrast to late DN, the initial decrease in AER with antihypertensive therapy was not shown to predict the subsequent rate of decline of GFR in early DN. It follows that assessment of renoprotection during antihypertensive therapy in early nephropathy should be based not only on albuminuria but also on the GFR response.

Divergences in antihypertensive therapy in special situations in nephrology

CONTEXT AND OBJECTIVE

The choice of an antihypertensive drug is based on several criteria and specific situations give rise to doubt and controversy. The aim here was to evaluate physicians approaches towards treatment with antihypertensive agents in specific situations.

DESIGN AND SETTING

Cross-sectional study, at Universidade Federal de São Paulo, São Paulo.

METHODS

A questionnaire was applied during a nephrology meeting to evaluate individual approaches towards each hypothetical clinical situation. The questionnaire consisted of five multiple-choice questions (clinical cases) concerning controversial aspects of antihypertensive therapy.

RESULTS

A total of 165 questionnaires were analyzed. Most participants were nephrologists (93.2%). There was a preference for angiotensin-converting enzyme (ACE) inhibitors in at least two of the cases. Only 57.2% of the physicians were correct in choosing beta-blockers as the first-line drugs for patients with ischemic coronary disease. Moreover, 66.2% chose ACE inhibitors as the first-line drugs for patients with chronic kidney disease and proteinuria. About 5% of the physicians did not follow the current recommendations for the use of ACE inhibitors in diabetic patients with microalbuminuria. The most controversial question concerned the first-line drug for advanced chronic kidney disease. Most physicians were correct in choosing calcium channel blockers and avoiding ACE inhibitors in renovascular hypertension in the case of a patient with a single functioning kidney.

CONCLUSIONS

Most physicians adopted the correct approach, but some had an alternative strategy for the same situations that was not based on evidence.

Novel insights in the treatment of diabetic nephropathy

Diabetes is currently one of the leading causes of end-stage renal failure requiring renal replacement therapy in the Western World. About 15% to 20% of type 1 diabetic patients and 30% to 40% of type 2 diabetic patients will eventually develop end-stage renal failure. To prevent the development or progression of diabetic kidney disease, good glycaemic control remains the cornerstone in the management of diabetic patients. Beyond glycaemic control, other metabolic factors have been shown to be involved in the development of diabetic kidney disease, i.e. advanced glycation endproducts (AGEs) and the aldose reductase pathway. Furthermore, an adequate control of high blood pressure and treatment of microalbuminuria are major therapeutic targes. To achieve adequate blood pressure control, a combination therapy with different classes of antihypertensive agents is often necessary, especially including angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. Other vasoactive factors involved in diabetic nephropathy such as endothelin and nitric oxide will be covered briefly. Besides hyperglycaemia and high blood pressure, other risk factors have been identified in the development or progression of diabetic kidney disease: smoking, hyperlipidaemia, obesity and high protein intake. Their impact on renal function will be highlighted. Finally, recent research has also identified intracellular pathways such as the diacylglycerol-protein kinase C pathway and several growth factors, such as growth hormone, insulin-like growth factor, transforming growth factor-beta, vascular endothelial growth factor, and platelet derived growth factor as players in diabetic kidney disease.

Effects of perindopril in hypertensive patients with or without type 2 diabetes mellitus, and with altered insulin sensitivity

Impaired insulin sensitivity and hypertension are risk factors for atherosclerosis, which in turn leads to a variety of cardiovascular diseases. In both conditions, the risks of morbidity and mortality appear to be further increased. Impaired insulin sensitivity is also a precursor for diabetes. The renin-angiotensin-aldosterone system (RAAS) is implicated in the development of both hypertension and insulin resistance. Antihypertensive agents that act by blocking the RAAS, such as angiotensin-converting enzyme (ACE) inhibitors, may improve insulin sensitivity and therefore prevent the deleterious consequences of insulin resistance, including type 2 diabetes. ACE inhibitors appear to improve insulin sensitivity in patients with hypertension and insulin resistance, including diabetes. This review assesses the literature surrounding the use of the ACE inhibitor perindopril in patients with hypertension and varying degrees of insulin resistance, including the effects of perindopril in preventing the development of diabetes and subsequent cardiovascular morbidity and mortality.

Advanced glycation end products decrease mesangial cell MMP-7: a role in matrix accumulation in diabetic nephropathy?

Increased extracellular matrix material is a pathological hallmark of diabetic nephropathy. In addition to collagens, a variety of non-collagenous glycoproteins such as fibronectin also accumulate in the kidney of diabetics. The effect of diabetes on degradative pathways, in particular those involving non-collagenous proteins, are relatively unexplored. In this study, we determined the expression of the major matrix metalloproteinase (MMP) responsible for degrading the non-collagenous matrix glycoprotein fibronectin. Furthermore, the modulation of these MMPs by advanced glycation end products (AGE), a key factor in the diabetic milieu, was explored. Exposure of mesangial cells to AGEs led to a significant reduction in MMP-7, but not MMP-3 or -10. MMP-7 expression was normalized by both aminoguanidine, an inhibitor of glycation product formation, or by a neutralizing anti-transforming growth factor-beta (TGF-beta) antibody. In streptozotocin-induced diabetic rats, the diminution in MMP-7 expression and excessive fibronectin accumulation were attenuated by aminoguanidine. Humans with type 2 diabetes and nephropathy displayed similar alterations in MMP-7 to their rodent counterparts. Our findings suggest that diminished expression of the glycoprotein-degrading enzyme, MMP-7, may play a role in fibronectin accumulation in the diabetic kidney in response to AGEs and/or TGF-beta.

Improving outcomes in diabetes and chronic kidney disease: the basis for Canadian guidelines

The prevalence of diabetes is on the rise in Canada, and there has been a corresponding increase in the rate of micro- and macrovascular complications. Among the worst of these is chronic kidney disease (CKD). It may be diagnosed either through the detection of persistent albuminuria or an estimated glomerular filtration rate that is persistently less than 60 mL/min/1.73 m2. Patients with diabetes and CKD have a lower quality of life and higher health care costs, and face the prospect of end-stage renal disease requiring dialysis. More importantly, this group has an extremely elevated cardiovascular risk and correspondingly reduced survival. Research over several decades has led to two important conclusions. First, progressive worsening of kidney disease is not inevitable in people with diabetes; it can be slowed or even stopped. Second, the elevated cardiovascular risk in this population can be significantly reduced through an aggressive approach to cardiovascular risk factor reduction. These conclusions have prompted Canadian guideline groups, such as the Canadian Diabetes Association and the Canadian Hypertension Education Program, to release clinical practice guidelines that address the management of people with diabetes and CKD. In the present article, the studies that have influenced these Canadian guidelines are examined, and areas in which further research is still required are identified.

Blood pressure lowering for the prevention and treatment of diabetic kidney disease

The current pandemic of diabetes mellitus will inevitably be followed by an epidemic of chronic kidney disease. It is anticipated that 25-40% of patients with type 1 diabetes and 5-40% of patients with type 2 diabetes will ultimately develop diabetic kidney disease. The control of blood pressure represents a key component for the prevention and management of diabetic nephropathy. There is a strong epidemiological connection between hypertension in diabetes and adverse outcomes in diabetes. Hypertension is closely linked to insulin resistance as part of the 'metabolic syndrome'. Diabetic nephropathy may lead to hypertension through direct actions on renal sodium handling, vascular compliance and vasomotor function. Recent clinical trials also support the utility of blood pressure reduction in the prevention of diabetic kidney disease. In patients with normoalbuminuria, transition to microalbuminuria can be prevented by blood pressure reduction. This action appears to be significant regardless of whether patients have elevated blood pressure or not. The efficacy of ACE inhibition appears to be greater than that achieved by other agents with a similar degree of blood pressure reduction; although large observational studies suggest the risk of microalbuminuria may be reduced by blood pressure reduction, regardless of modality. In patients with established microalbuminuria, ACE inhibitors and angiotensin receptor antagonists (angiotensin receptor blockers [ARBs]) consistently reduce the risk of progression from microalbuminuria to macroalbuminuria, over and above their antihypertensive actions. The clinical utility of combining these strategies remains to be established. In patients with overt nephropathy, blood pressure reduction is associated with reduced urinary albumin excretion and, subsequently, a reduced risk of renal impairment or end stage renal disease. In addition to actions on systemic blood pressure, it is now clear that ACE inhibitors and ARBs also reduce proteinuria in patients with diabetes. This anti-proteinuric activity is distinct from other antihypertensive agents and diuretics. Although there is a clear physiological rationale for blockade of the renin angiotensin system, which is strongly supported by clinical studies, to achieve the optimal lowering of blood pressure, particularly in the setting of established diabetic renal disease, a number of different antihypertensive agents will always be needed. In the end, the choice of agents should be individualised to achieve the maximal tolerated reduction in blood pressure and albuminuria. Ultimately, no matter how it is achieved, so long as it is achieved, renal risk can be reduced by agents that lower blood pressure and albuminuria.

Angiotensin converting enzyme inhibitors and angiotensin II receptor antagonists for preventing the progression of diabetic kidney disease

BACKGROUND

Angiotensin converting enzyme inhibitors (ACEi) and angiotensin II receptor antagonists (AIIRA) are considered to be equally effective for patients with diabetic kidney disease (DKD), but renal and not mortality outcomes have usually been considered.

OBJECTIVES

To evaluate the benefits and harms ACEi and AIIRA in patients with DKD.

SEARCH STRATEGY

We searched MEDLINE (1966 to December 2005), EMBASE (1980 to December 2005), the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library issue 4 2005) and contacted known investigators.

SELECTION CRITERIA

Studies comparing ACEi or AIIRA with placebo or each other in patients with DKD were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted data. Statistical analyses were performed using the random effects model and results expressed as relative risk (RR) with 95% confidence intervals (CI). Heterogeneity among studies was explored using the Cochran Q statistic and the I(2) test, subgroup analyses and random effects metaregression.

MAIN RESULTS

Fifty studies (13,215 patients) were identified. Thirty eight compared ACEi with placebo, five compared AIIRA with placebo and seven compared ACEi and AIIRA directly. There was no significant difference in the risk of all-cause mortality for ACEi versus placebo (RR 0.91, 95% CI 0.71 to 1.17) and AIIRA versus placebo (RR 0.99, 95% CI 0.85 to 1.17). A subgroup analysis of studies using full-dose ACEi versus studies using half or less than half the maximum tolerable dose of ACEi showed a significant reduction in the risk of all-cause mortality with the use of full-dose ACEi (RR 0.78, 95% CI 0.61 to 0.98). Baseline mortality rates were similar in the ACEi and AIIRA studies. The effects of ACEi and AIIRA on renal outcomes (ESKD, doubling of creatinine, prevention of progression of micro- to macroalbuminuria, remission of micro- to normoalbuminuria) were similarly beneficial. Reliable estimates of effect of ACEi versus AIIRA could not be obtained from the three studies in which they were compared directly because of their small sample size.

AUTHORS' CONCLUSIONS

Although the survival benefits of ACEi are known for patients with DKD, the relative effects on survival of ACEi with AIIRA are unknown due to the lack of adequate direct comparison studies. In placebo controlled studies, only ACEi (at the maximum tolerable dose, but not lower so-called renal doses) were found to significantly reduce the risk of all-cause mortality. Renal and toxicity profiles of these two classes of agents were not significantly different.

Angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers for prevention and treatment of nephropathy associated with type 2 diabetes mellitus

Renal complications resulting from type 2 diabetes mellitus are costly and common. Finding optimal therapy is important for the prevention and management of diabetic nephropathy. Research has focused on antihypertensive agents that modify the renin-angiotensin-aldosterone system. Because of their effects on the glomerulus, angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) have been studied as interventions at various stages of diabetic nephropathy. The ACE inhibitors may delay the progression to microalbuminuria and then clinical albuminuria. The ARBs decrease albuminuria in patients with microalbuminuria and decrease adverse renal events, specifically the progression to end-stage renal disease in patients with clinical albuminuria and hypertension. Limited data suggest that combination therapy with ACE inhibitors and ARBs may slow the progression of microalbuminuria to clinical albuminuria. Because of the variability in degree of albuminuria evaluated and in study designs (numbers of patients, study duration, drug dosages, and outcomes measured), a detailed review of the available literature about ACE inhibitors and ARBs in the prevention or treatment of diabetic nephropathy may provide insight to clinicians.

Serum lipids and the progression of nephropathy in type 1 diabetes

OBJECTIVE

Dyslipidemia contributes to the progression of microvascular disease in diabetes. However, different lipid variables may be important at different stages of nephropathy. This study examines the pattern of dyslipidemia associated with the progression of nephropathy in patients with type 1 diabetes.

RESEARCH DESIGN AND METHODS

A total of 152 patients with type 1 diabetes were recruited in order to represent various phases of nephropathy. Patients were followed for 8-9 years, during which time they received standard care. Renal progression was defined a priori as a doubling in albumin excretion (in patients with normo- or microalbuminuria) or a decline in creatinine clearance (in those with macroalbuminuria). A panel of lipid variables was determined and correlated with indexes of progression.

RESULTS

In patients with normoalbuminuria (n = 66), progression was associated with male sex (P < 0.05), borderline albuminuria (P = 0.02), and LDL-free cholesterol (P = 0.02). In patients with microalbuminuria (n = 51), progression was independently associated with triglyceride content of VLDL and intermediate-density lipoprotein (both P < 0.05). In patients with macroalbuminuria (n = 36), a significant decline in the renal function (>3 ml x min(-1) x year(-1)) was independently associated with poor glycemic control, hypertension, and LDL size (P < 0.05). When all patients with progressive nephropathy were analyzed together, only LDL cholesterol was predictive on multivariate analysis (P < 0.05), which masked the importance of triglyceride enrichment in microalbuminuria.

CONCLUSIONS

Lipid variables are associated with progression of diabetic kidney disease, but the relationship is not the same at all stages. This finding has implications for the design of renoprotective strategies and the interpretation of clinical trials in type 1 diabetes.

Renal protection in hypertensive patients: selection of antihypertensive therapy

Hypertension is common in chronic renal disease and is a risk factor for the faster progression of renal damage, and reduction of blood pressure (BP) is an efficient way of preventing or slowing the progression of this damage. International guidelines recommend lowering BP to 140/90 mm Hg or less in patients with uncomplicated hypertension, and to 130/80 mm Hg or less for patients with diabetic or chronic renal disease. The attainment of these goals needs to be aggressively pursued with multidrug antihypertensive regimens, if needed. The pathogenesis of hypertensive renal damage involves mediators from various extracellular systems, including the renin-angiotensin system (RAS). Proteinuria, which occurs as a consequence of elevated intraglomerular pressure, is also directly nephrotoxic. As well as protecting the kidneys by reducing BP, antihypertensive drugs can also have direct effects on intrarenal mechanisms of damage, such as increased glomerular pressure and proteinuria. Antihypertensive drugs that have direct effects on intrarenal mechanisms may, therefore, have nephroprotective effects additional to those resulting from reductions in arterial BP. Whereas BP-lowering effects are common to all antihypertensive drugs, intrarenal effects differ between classes and between individual drugs within certain classes. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARB) have beneficial effects on proteinuria and declining renal function that appear to be mediated by factors additional to their effects on BP. These RAS inhibitors are recommended as a first-line antihypertensive approach in patients with chronic kidney disease. The addition of diuretics and calcium channel antagonists to RAS inhibitor therapy is also considered to be a rational strategy to reduce BP and preserve renal function. Calcium channel antagonists are a highly heterogeneous class of compounds, and it appears that some agents are more suitable for use in patients with chronic renal disease than others. Manidipine is a third-generation dihydropyridine (DHP) calcium channel antagonist that blocks both L and T-type calcium channels. Unlike older-generation DHPs, which preferentially act on L-type channels, manidipine has been shown to have beneficial effects on intrarenal haemodynamics, proteinuria and other measures of renal functional decline in the first clinical trials involving hypertensive patients with chronic renal failure. Preliminary results from a trial in diabetic patients who had uncontrolled hypertension and microalbuminuria despite optimal therapy with an ACE inhibitor or an ARB suggest that manidipine may be an excellent antihypertensive drug in combination with RAS inhibitor treatment in order to normalise BP and albumin excretion in patients with diabetes.

Increased tubular organic ion clearance following chronic ACE inhibition in patients with type 1 diabetes

BACKGROUND

The tubular excretion of creatinine significantly contributes to its clearance. Administration of an angtiotensin-converting enzyme (ACE) inhibitor is associated with increased organic ion clearance in experimental diabetes. This study examines the effect and implications of chronic ACE inhibition on renal organic ion excretion in patients with type 1 diabetes.

METHODS

Samples were obtained from the Melbourne Diabetic Nephropathy Study Group (MDNSG) that randomized patients to receive perindopril (N= 11), nifedipine (N= 11), or placebo (N= 8). Albumin excretion rate, creatinine clearance, and isotopic glomerular filtration rate (GFR) were assessed at baseline and after 24 months. In addition, the clearance of the endogenous cations N-methylynicotinamide (NMN), creatinine, and the anion hippurate were determined by high-performance liquid chromatography (HPLC).

RESULTS

Following treatment with the ACE inhibitor, perindopril, renal clearance of NMN was increased (+96%) (P < 0.05). There was no difference in patients treated with nifedipine (P= 0.25) and NMN clearance fell in the placebo-treated patients (-26%) (P < 0.05). Changes in NMN clearance were unaffected after adjusting for the effects of perindopril on GFR. However, they were attenuated after adjusting for hippurate clearance, a marker of renal blood flow. This effect of perindopril on NMN clearance was seen in both men and women, regardless of baseline clearance and was correlated with reduced albuminuria following perindopril treatment.

CONCLUSION

Organic ion clearance is increased in patients with diabetes following chronic ACE inhibition. This is consistent with experimental models showing increased ion transporter expression and improved tubular blood flow, following blockade of the renin-angiotensin system (RAS). These findings may have implications for the interpretation of creatinine-based indices in patients with diabetes.

Modulation of Soluble Receptor for Advanced Glycation End Products by Angiotensin-Converting Enzyme-1 Inhibition in Diabetic Nephropathy

Recent studies have identified that first-line renoprotective agents that interrupt the renin-angiotensin system not only reduce BP but also can attenuate advanced glycation end product (AGE) accumulation. This study used in vitro, preclinical, and human approaches to explore the potential effects of these agents on the modulation of the receptor for AGE (RAGE). Bovine aortic endothelial cells that were exposed to the angiotensin-converting enzyme inhibitor (ACEi) ramiprilat in the presence of high glucose demonstrated a significant increase in soluble RAGE (sRAGE) secreted into the medium. In streptozotocin-induced diabetic rats, ramipril treatment (ACEi) at 3 mg/L for 24 wk reduced the accumulation of skin collagen-linked carboxymethyllysine and pentosidine, as well as circulating and renal AGE. Renal gene upregulation of total RAGE (all three splice variants) was observed in ACEi-treated animals. There was a specific increase in the gene expression of the splice variant C-truncated RAGE (sRAGE). There were also increases in sRAGE protein identified within renal cells with ACEi treatment, which showed AGE-binding ability. This was associated with decreases in renal full-length RAGE protein from ACEi-treated rats. Decreases in plasma soluble RAGE that were significantly increased by ACEi treatment were also identified in diabetic rats. Similarly, there was a significant increase in plasma sRAGE in patients who had type 1 diabetes and were treated with the ACEi perindopril. Complexes between sRAGE and carboxymethyllysine were identified in human and rodent diabetic plasma. It is postulated that ACE inhibition reduces the accumulation of AGE in diabetes partly by increasing the production and secretion of sRAGE into plasma.

From hyperglycemia to diabetic kidney disease: the role of metabolic, hemodynamic, intracellular factors and growth factors/cytokines

At present, diabetic kidney disease affects about 15-25% of type 1 and 30-40% of type 2 diabetic patients. Several decades of extensive research has elucidated various pathways to be implicated in the development of diabetic kidney disease. This review focuses on the metabolic factors beyond blood glucose that are involved in the pathogenesis of diabetic kidney disease, i.e., advanced glycation end-products and the aldose reductase system. Furthermore, the contribution of hemodynamic factors, the renin-angiotensin system, the endothelin system, and the nitric oxide system, as well as the prominent role of the intracellular signaling molecule protein kinase C are discussed. Finally, the respective roles of TGF-beta, GH and IGFs, vascular endothelial growth factor, and platelet-derived growth factor are covered. The complex interplay between these different pathways will be highlighted. A brief introduction to each system and description of its expression in the normal kidney is followed by in vitro, experimental, and clinical evidence addressing the role of the system in diabetic kidney disease. Finally, well-known and potential therapeutic strategies targeting each system are discussed, ending with an overall conclusion.

Long-term renoprotection by perindopril or nifedipine in non-hypertensive patients with Type 2 diabetes and microalbuminuria

AIMS

To assess the efficacy of an angiotensin converting enzyme (ACE) inhibitor (perindopril), a dihydropyridine calcium channel blocker (sustained release nifedipine) and placebo in preventing the progression of albuminuria and decline in glomerular filtration rate (GFR) in patients with Type 2 diabetes and microalbuminaria.

METHODS

A prospective, randomized, open, blinded end point study of 77 patients allocated to three treatment groups (23 perindopril, 27 nifedipine, 27 placebo). Drug doses were adjusted to achieve a decrease in diastolic blood pressure (DBP) of 5 mmHg in the first 3 months and additional therapy was given if hypertension developed (supine DBP > 90 mmHg and/or systolic blood pressure (SBP) > 140 mmHg if < or = 40 years; supine DBP > 90 mmHg and/or SBP > 160 mmHg if > 40 years). Median follow-up was 66 months, with 37 patients being followed for at least 6 years.

RESULTS

Blood pressure remained within the non-hypertensive range in 83% of perindopril-, 95% of nifedipine- and 30% of placebo-treated patients (P < 0.01). In the first 12 months albumin excretion rate (AER) decreased by 47% only in the perindopril group (P = 0.04). From 12 to 72 months, AER gradients increased by 27% per year only in the placebo group (P < 0.01). After 6 years, macroalbuminuria had developed in 7/15 placebo compared with 2/11 in perindopril and 1/11 nifedipine-treated patients (P = 0.05). GFR did not change in the first 12 months, but thereafter the median GFR gradient (ml/min/1.73 m(2) per year) was -2.4 (P < 0.01) for perindopril-, -1.3 (P = 0.26) for nifedipine- and -4.2 (P = 0.01) for placebo-treated patients. The rate of decline in GFR for the study group as a whole from 12 months to the end of follow-up correlated negatively with mean arterial pressure (MAP) (r = -0.38, P < 0.01). During a 3-month treatment pause in 29 patients AER tended to increase only in the perindopril group (P < 0.07).

CONCLUSIONS

Long-term control of blood pressure with perindopril or nifedipine stabilizes AER and attenuates GFR decline in proportion to MAP in non-hypertensive patients with Type 2 diabetes and microalbuminuria.

Calcium channel blockers, either amlodipine or mibefradil, ameliorate renal injury in experimental diabetes

BACKGROUND

Diabetic nephropathy is associated with increased albuminuria and accumulation of extracellular matrix proteins within the kidney. Clinical studies have shown some beneficial effects of calcium channel blockers (CCB) on diabetic nephropathy, even though they are generally considered to be less renoprotective than agents that interrupt the renin angiotensin system. However, effects of CCBs on renal injury, and in particular, expression of extracellular matrix proteins in a model of normotensive diabetic nephropathy, are poorly characterized.

METHODS

Experimental diabetes was induced by injection of streptozocin in Sprague-Dawley rats. Amlodipine, a CCB which blocks the L channel, and mibefradil, a CCB blocking the T as well as the L channels, were given to diabetic rats for six months. Albumin excretion rate (AER), pathologic injury, and expression of the extracellular matrix proteins, collagen I, and fibronectin were assessed.

RESULTS

Increased AER in diabetic rats (13.2 x//1.3 mg/d, geometric mean x// tolerance factor) was attenuated by either amlodipine (3.2 x// 1.4 mg/d) or mibefradil (2.6 x// 1.4 mg/d). Increased glomerulosclerosis and tubulointerstitial injury in diabetic animals were attenuated by amlodipine and mibefradil. There was increased collagen accumulation in the kidney of diabetic rats as assessed by picro-sirius red staining. Gene expression of both collagen I and fibronectin were also increased in the kidneys from diabetic animals, as assessed by reverse transcription-polymerase chain reaction (RT-PCR). These markers of fibrosis were attenuated by treatment with either amlodipine or mibefradil. Blood pressure in diabetic rats (136 +/- 2 mm Hg) was modestly reduced by amlodipine (126 +/- 3 mm Hg) but not by mibefradil treatment (134 +/- 3 mm Hg).

CONCLUSION

Calcium channel blockers attenuated albuminuria, pathologic injury, and accumulation of extracellular matrix proteins in this normotensive model of diabetic nephropathy. These findings suggest that CCBs may be useful in preventing pathologic injury in the diabetic kidney.

Antiproteinuric effect of RAS blockade: New mechanisms

Experimental and clinical studies have shown that blockade of the renin-angiotensin system (RAS) is effective in reducing proteinuria in conditions such as diabetes by reducing systemic and intraglomerular hydrostatic pressure. However, increasing evidence suggests that nonhemodynamic effects, such as preservation of the podocyte slit diaphragm structure and function, may also mediate the antiproteinuric effects of RAS blockade. In this review, we analyze in detail the evidence for known and novel mechanisms considered to play important roles in mediating the antiproteinuric effect of RAS blockers, with a particular focus on diabetic nephropathy.

New insights into the significance of microalbuminuria

PURPOSE OF REVIEW

This review summarizes recent work that has explored the association between microalbuminuria and adverse clinical outcomes in the presence and absence of diabetes.

RECENT FINDINGS

Recent investigations have documented the prevalence of microalbuminuria in the general community and have also highlighted the continuous relationship between the level of urinary albumin excretion and clinical endpoints. Even below traditional microalbuminuria thresholds, urinary albumin levels appear to correlate with clinical outcomes. Microalbuminuria is becoming increasingly recognized as an independent risk factor for cardiovascular morbidity and mortality. At least for subjects with type 2 diabetes and microalbuminuria, intensive, multifactorial interventions can reduce the risk of cardiovascular events by about 50%. Although several studies have found an association between microalbuminuria and surrogate measurements of vascular disease, the exact molecular mechanisms linking an increase in urinary albumin excretion and vascular disease are still unknown. Microalbuminuria also has a well-documented association with progressive diabetic renal disease but recent studies have suggested that the prognostic significance of microalbuminuria in this regard may not be as powerful as originally reported.

SUMMARY

Aggressive, multifactorial interventions, including the use of drugs that interrupt the renin-angiotensin system are strongly recommended for patients with diabetes and micro-albuminuria to ameliorate the progression of renal and vascular complications. This approach should also possibly apply to microalbuminuric subjects without diabetes. The relationship between microalbuminuria and progressive diabetic renal disease requires re-evaluation given temporal trends in the prevention and treatment of diabetic complications.

Use of calcium antagonists in renal patients: therapeutic benefit or medical malpractice?

In patients with kidney disease, control of hypertension is paramount in helping to slow down the progression of both diabetic and nondiabetic nephropathy. A significant amount of data have been published that suggest blockade of the renin-angiotensin system should be considered as first-line therapy for patients with kidney disease. Meanwhile, some studies have suggested that the use of calcium channel blockers may have deleterious effects on patients with kidney disease. This manuscript reviews the renal outcomes of trials in which calcium channel blockers were included in the management of patients with and without kidney disease. The data suggest that agents that block the renin-angiotensin system are superior to calcium channel blockers in protecting against progressive kidney disease. However, there is no conclusive evidence that calcium channel blockers are injurious to the kidney, and they may be particularly beneficial in post-renal transplant patients.

Urinary connective tissue growth factor excretion in patients with type 1 diabetes and nephropathy

OBJECTIVE

Excretion of growth factors in the urine has been implicated in the pathogenesis of tubulointerstitial disease that characterizes proteinuric renal disease. In this cross-sectional study, we sought to examine the urinary excretion of the profibrotic cytokine connective tissue growth factor (CTGF) in type 1 diabetic patients with incipient and overt diabetic nephropathy.

RESEARCH DESIGN AND METHODS

We recruited 31 subjects with type 1 diabetes from a hospital diabetes outpatient clinic. Of these, 10 subjects were normoalbuminuric, 8 were microalbuminuric and not receiving ACE inhibitor treatment, and 13 were macroalbuminuric, 8 of whom were receiving ACE inhibitor treatment. Urinary CTGF NH(2)-terminal fragment (CTGF-N) was determined by enzyme-linked immunosorbent assay and expressed relative to urinary creatinine.

RESULTS

Urinary CTGF-N was closely correlated with the degree of albuminuria (r = 0.76, P < 0.001). In comparison with normoalbuminuric subjects, urinary CTGF-N was increased 10- and 100-fold in micro- and untreated macroalbuminuric subjects, respectively (CTGF-N-to-creatinine ratio: normoalbuminuria 0.23 x// 1.3 ng/mg, microalbuminuria 2.1 x// 1.7 ng/mg, untreated macroalbuminuria 203 x// 3.8 ng/mg, and geometric mean x// tolerance factor; P < 0.05 for normoalbuminuria versus microalbuminuria, P < 0.001 for microalbuminuria versus macroalbuminuria). Urinary CTGF-N was lower (<30-fold) in macroalbuminuric subjects treated with ACE inhibitors (6.5 x// 1.7 ng/mg; P < 0.01 vs. untreated macroalbuminuria) compared with their untreated counterparts.

CONCLUSIONS

In this cross-sectional study, the magnitude of urinary CTGF-N excretion was related to the severity of diabetic nephropathy. In the context of its known profibrotic actions, these findings suggest that CTGF may contribute to the chronic tubulointerstitial fibrosis that accompanies proteinuric renal disease. Prospective and interventional studies will be needed to determine whether urinary CTGF-N may provide a reliable surrogate marker of renal injury and a meaningful indicator of response to therapy.

The renin-angiotensin system and the long-term complications of diabetes: pathophysiological and therapeutic considerations

The relationship between the renin-angiotensin system (RAS) and the progression of diabetic renal disease has been a major focus of investigation over the past 20 years. More recently, experimental and clinical studies have also suggested that the RAS may have a pathogenetic role at other sites of micro- and macrovascular injury in diabetes. Complementing major advances into the understanding of the local, as distinct from the systemic RAS, a number of large clinical trials have examined whether blockade of the RAS might provide protection from the long-term complications of diabetes, beyond that due to blood pressure reduction alone. While some controversy remains, these studies have, in general, suggested that angiotensin converting enzyme (ACE) inhibition and more recently, angiotensin receptor blockade reduce the development and progression of diabetic nephropathy, cardiovascular disease and possibly retinopathy. This review will focus on recent developments in our understanding of the tissue-based RAS and its role in end-organ injury in diabetes, the results of recent clinical trials and newer strategies for the pharmacological manipulation of the RAS.

Microalbuminuria and hypertension with focus on type 1 and type 2 diabetes

Microalbuminuria and hypertension with Over the past decade, there has been considerable focus on the concept of microalbuminuria, not only because it predicts renal disease in type 1 and type 2 diabetes, but also because it relates to premature mortality in the diabetic and in the general population. More importantly, intervention at this stage is now possible with the perspective of preserving glomerular filtration rate (GFR) and ameliorating cardiovascular disease and ensuing strong end-points. INITIAL STUDIES: The concept of microalbuminuria was introduced about 20 years ago and since then there has been a multitude of studies and papers on this subject using the original definition, but not always, in the US. Before that time it was suggested, mainly from the US, that diabetic renal disease was an untreatable relentlessly progressive condition.

GENETIC STUDIES

There is an overwhelming number of studies on genetics and diabetes and also covering the genetics of diabetic complications including nephropathy. However, so far the results are extremely disappointing. Patients at risk cannot be identified and genetic analyses are of no value as a guide to treatment. The notion that the development of complications is controlled mainly by a special genetic pattern is increasingly doubtful. In genetic studies, it is rather phenotypic well-accepted risk factors that dominate. STRUCTURAL BASIS OF MICROALBUMINURIA: Patients with microalbuminuria have significant abnormalities in the kidney, including glomeruli. This is quite clear in patients with type 1 diabetes, but is also seen in type 2 diabetes, where on the other hand, other risk factors such as hypertension and dyslipidaemia also seem to be of importance, including loss of autoregulation. Renal biopsies are generally not indicated in the management of diabetic patients. MICROALBUMINURIA AND EARLY MORTALITY: It is quite clear that microalbuminuria predicts early mortality both in type 1 and type 2 diabetes. The association to other risk factors may partly explain this--but this does not account for the whole picture. Endothelial dysfunction as well as inflammatory and arteriosclerotic abnormalities in blood vessels may be a relevant hypothesis that needs to be further explored along with other possibilities. CLINICAL COURSE AND ASSOCIATED ABNORMALITIES: The risk factor for progression in normoalbuminuric patients to microalbuminuria is higher than normal albumin excretion (strongest factor), poor glycaemic control, elevated blood pressure, and to some extent smoking. The clinical course of microalbuminuria is usually progressive, but with the more effective intervention now available we encounter that the so-called natural history (without intervention) is increasingly difficult to study. Microalbuminuria is clearly associated with a number of abnormalities, almost in all organs, but GFR is generally well preserved in spite of more advanced structural lesions. Therefore, microalbuminuria is an important marker for more pronounced diabetic vascular disease in general as well as for nephropathy. Regression to normoalbuminuria only rarely occurs during standard unchanged nonintensive treatment. TREATMENT STRATEGIES: The best possible glycaemic control is important in preventing and ameliorating the course of normo- and micro-albuminuria. Another major treatment strategy, especially in microalbuminuric patients, is antihypertensive treatment including inhibition of the renal angiotensin aldosterone system. Numerous new studies are available, both in type 1 and type 2 diabetes, documenting that not only microalbuminuria but also renal and cardiovascular complications in these patient are also far better controlled by early detection and treatment. Therefore, screening for microalbuminuria should be a strategy in all diabetes management followed by effective intervention as outlined in this paper.

Regression of albuminuria: latest evidence for a new approach

OBJECTIVE

To review the latest studies on antihypertensive strategies in the treatment of microalbuminuria, in order to highlight the association of microalbuminuria with hypertension and type 2 diabetes, the evidence for microalbuminuria as a risk factor for target-organ damage and mortality, and the prognostic significance of regression of microalbuminuria.

STUDY SELECTION

Randomized controlled trials in patients with hypertension, type 2 (non-insulin-dependent) diabetes mellitus and microalbuminuria, with changes in albumin excretion rate (AER) as a primary outcome measure.

RESULTS OF DATA ANALYSIS

Antihypertensive treatment is the most effective method for reducing microalbuminuria. Although microalbuminuria regression is related to reduction in blood pressure, antihypertensive drugs acting on the renin-angiotensin system have an antiproteinuric effect that is additional to that of blood pressure reduction. The combination of these agents with diuretics, even when used in low doses, may further reduce AER in these patients.

CONCLUSIONS

Blockade of the renin-angiotensin system with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers is a most effective means of treating microalbuminuria and preventing its progression to overt nephropathy and, perhaps, the associated cardiovascular disease. The effect of this strategy may be improved further with the use, as first-line treatment, of a combination of angiotensin-converting enzyme inhibitor and diuretic.